Poly(aryl ethers) have been known for about two decades; they are tough linear polymers that possess a number of attractive features such as excellent high temperature resistance, good electrical properties, and very good hydrolytic stability. Two poly(aryl ethers) are commercially available. A poly(aryl ether sulfone) is available from Imperial Chemical Industries Limited. It has repeating units of the following formula (1): ##STR1## It is produced by the polycondensation of 4-(4'-chlorophenylsulfonyl)phenol, as described in British Patent Specification No. 1,153,035. The polymer contains no aliphatic moieties and has a heat deflection temperature of approximately 210.degree. C. The other commercially available poly(aryl ether sulfone) is available from Union Carbide Corporation under the trademark UDEL.RTM.. It has a heat deflection temperature of about 180.degree. C. and repeating units of the following formula (2): ##STR2##
However, the solvent and chemical resistance of the poly(aryl ether sulfones) are only marginal.
Liquid crystalline aromatic polyesters are well known in the art. These liquid crystalline polyesters are described in, for example, U.S. Pat. Nos. 3,804,805; 3,637,595; 4,130,545; 4,161,470; 4,230,817 and 4,265,802. The liquid crystalline polyesters are characterized in that they exhibit optical anisotropy in the melt phase. Liquid crystalline polyesters are ordered, high strength materials, having very good high temperature properties; they are particularly suitable for high strength fibers and filaments. Their main drawback as molding materials resides in the anisotropy of properties displayed by molded parts. An excellent overview of liquid crystalline polyesters was published recently, see W. J. Jackson, Jr., Journal of Applied Polymer Science, Applied Polymer Symposium 41, 25-33 (1985).